Electromagnetic device



Filed Nov. 26, 1949 NVENTOR Cyril E.Boston.

ATTO NEY end of the arm I9. The arm is is mounted upon and secured to the shaft l2. One end of a spring 23 is attached to a bracket 2% which, in turn, is attached to the supporting structure it and the other end of the spring 23 is attached to an angularly disposed extension 25 on the arm lEl by means of a pin 26. A stirrup 2'! i attached to the clapper it by screws 23 and an adjustable stop screw 29 is provided in the stirrup 2'? for engaging the arm 59.

A tail piece Si is attached to the bottom of the clapper it by screws 32 and carries a pin 33. An adjustable screw 34 is provided in the supporting structure it for engaging the pin 33 to limit the opening movement of the clapper iii.

As shown, a movable contact arm 35 is rotatably mounted on the shaft I7 and is provided with" an adjustable screw 38 which is engaged by the pin 33 when the clapper i6 is actuated toward the core 52. The contact arm 35 car ries a contact member 3i which engages a fixed contact member 38 when the clapper it is in the open position as shown in Fig. 3. A spring 39 biases the contact arm 35 to maintain the contact members 3''! and 323 closed.

As shown most clearly in Figs. 2 and 3, a second movable contact arm 56 is rotatably mounted on the shaft ii. The arm All carries a contact member 22 which engages a fixed contact member t3. A compression spring it biases the arm ii to maintain the contact members 52 and 33 closed. An arm s5 is secured to the shaft ii and is provided with a lateral extension 36 which engages the contact arm 4! when the shaft ii is rotated a predetermined amount.

When a predetermined current flows through the coil it, the core i2 is sufficiently magnetized to attract the clapper it toward the core. Since the screw as in the stirrup 2's engages the arm iii, the clapper and the arm are moved simultaneously toward the core and are restrained by the spring 23 which, as previously explained, is attached to the arm [9.

The movement of the clapper is toward the core actuates the contact arm 35 by means of the pin 33 and the screw 36, thereby opening the contact members 3? and 38. As explained hereinbefore, these contact members may be so connected in the control system that their opening causes the steam to be shut off from the turbine which drives the generator. The movement of the arm i9 along with the clapper it rotates the shaft 5? since the arm is is secured to the shaft ll. However, the rotation of the shaft ii is not suficient at this time to cause the extension it of the arm :35 to engage the contact arm ll. Thus, the arm 55 functions as a lostmotion connection between the shaft ii and the contact arm ill.

As shown most clearly in Fig. l, a non-magnetic spacing member 4? is disposed on the end of the core 52, thereby preventing the clapper it from directly engaging the core I2. When the clapper it engages the spacer il, the plunger it is in alignment with the hole iii in the core l2. Because of the fact that the clapper it does not come into direct contact with the core l2, there is a resultant pull on the plunger is, which, if the current flowing through the coil it increases to an amount which indicates a damaging fault in the electrical apparatus, pulls the plunger it into the hole 53. The clapper it cannot follow the movement of the plunger 48. Therefore, the arm is i disengaged from the screw is in the stirrup 2?, but the magnetic pull on the plunger i8 must still overcome the tension of the spring 23-.

The additional movement of the arm it rotates the shaft [1 sufiiciently to cause the extension id on the arm 45 to engage the contact arm ll, thereby opening the contact members 32 and 43. As explained hereinbefore, these contact members may be so connected in the control system that their opening causes the opening of the circuit breaker in the main power circuit, thereby pro tecting the electrical apparatus against serious injury.

From the foregoing description it is apparent that I have provided a single relay which performs the functions normally performed by two separate relays, The present relay may be constructed at a slight increase in the cost of one of the two relays normally required to perform the functions herein described, and at no increase in the mounting dimensions of one or" the previous relays. Thus, a saving may be made in both the cost of the apparatus and the space required to mount the apparatus in a locomotive or other railway vehicle.

Ihe present relay may be so constructed and adjusted that the differential between the normal overload current and an excessive overload current may be made anything desired within reasonable limits. While the present relay is particularly suitable for utilization in the control system for a steam turbine-electric locomotive, it is not necessarily limited in its application to such a system.

Since numerous changes may be made in the above-described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. An electromagnetic device comprising: a supporting structure including a magnet-frame, said magnet-frame including a core having a hole in the end thereof; an electric-current excitingmeans for producing a magnetic flux in the core; a first armature-means, comprising an openbiased clapper pivotally mounted on the supporting structure, said clapper being mounted and biased in such position as to be magnetically attracted toward the end of the core in response to a predetermined amount of current flowing through the exciting-means, said clapper having a hole therein in alinement with the hole in the core; a second armature-means comprising an open-biased movably mounted plunger disposed within said hole in the clapper; a means for lineiting the opening-movement oi the plunger with respect to the clapper whereby the plunger moves jointly with the clapper when the clapper moves toward the core; and marginal biasing-means for biasing said plunger so as to permit the same to be further magnetically attracted, and movable down into the hole in the core, moving independently of the clapper, in response to a larger predetermined amount of current flowing through the exciting-means.

2. The invention as defined in claim 1, characterized by the principal bias-producing means, for both said clapper and said plunger, being a single biasing-means for biasing said plunger away from said core,

3. The invention as defined in claim 1, characterized by the second armature-means also including a plunger-arm, pivotally mounted on the supporting structure, for supporting said plunger; and the principal bias-producing means, for both said clapper and said plunger, being a single biasing-means for biasing said plunger-arm away from said core.

4. The invention as defined in claim 3, in combination with: a first motion-transmitting means, for responding to the attractive-movement of said clapper; and a second motion-transmitting means, for selectively responding to only the independent attractive-movement of the plunger.

5. The invention as defined in claim 3, characterized by the pivotal mounting-means, for both said clapper and said plunger-arm, including a shaft rotatably mounted in the supporting structure; the clapper being rotatably mounted on said shaft; and the plunger-arm being secured to said shaft.

6. The invention as defined in claim 5, in combination with: a first motion-transmitting means, for responding to the movement of said clapper;

and a second motion-transmitting means, including a lost-motion connection, for responding only to the final independent attractive-movement of said plunger-arm and shaft.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,053,489 Frost Feb. 18, 1913 1,331,882 Stone Feb. 24, 1920 1,429,009 Wynne Sept. 12, 1922 1,609,324 Stolp Dec. 7, 1926 1,726,164 Queeney Aug. 27, 1929 1,863,836 Derby et a1 June 21, 1932 2,096,502 Wetzel Oct. 19, 1937 2,505,849 Bevis et a1. May 2, 1950 FOREIGN PATENTS Number Country Date 566,075 Great Britain Dec. 12, 1944 

